If you have an ulcer can you still have gastric byp surgery?

I am currently on the waiting list to have a Gastric Byp Roux en Youx (in the next eight weeks). The surgery is to be performed as open surgery, however my G.P. feels i may have a stomach ulcer (due to my syptoms) i take omeprazole 40mg a day and i am wondering wether it is safe to have the op if i have an ulcer? If any one in the medical proffesion could please help with my query id really appreciate it.